A study examined the effect of geographic mobility on elementary school students' achievement. Although such mobility, which requires students to make multiple moves among schools, can have a negative impact on academic achievement, the hypothesis for the study was that it was not a determining factor in reading achievement test scores. Subjects were 157 fourth and fifth grade students, who were a representative sample of a multiethnic, socioeconomic group in a suburban elementary school district in New Jersey. Students were divided into four groups for comparison: Group A, students who have consistently attended the same school since first grade; Group B, those attending two schools, changing after first grade; Group C, students attending three schools; and Group D, those attending four to six schools. Data were obtained from reading scores from the Iowa Tests of Basic Skills administered in spring, 1995. Results indicated that, although the difference in attained reading scores between pupils who had moved only once and those who had attended the same school were relatively small, significant differences occurred between those who had attended one or two schools and those who had attended three or more schools. Findings revealed the hypothesis that mobility would not be a factor in reading achievement was not correct. Further research is suggested to determine the socioeconomic factors involved in mobility and their effect on students' academic achievement. (Four tables of data are included; 16 references, data for the 4 study groups, and related research are appended.) (Author/CR)